How can I render a 2D background that covers the whole screen while still allowing me to place player characters on top of it?

[hahsdjab1]

I don’t want to use tile map, because I fear I cannot make tile map fill the screen on any display. Also, this background will not move, and the entire background will only take up the one full screen that does not move.

I fear if I use widget, that I will not be able to put Player characters and NPCs in front of the widget background at designated positions with colliders.